The BZ oilfield in Bohai

known for its buried hill carbonate reservoir

is currently in the middle to late stages of development. The reservoir is characterized by strong heterogeneity and a complex distribution of fractures and vugs

leading to challenges such as complicated production behavior

rapidly declining output

and significant discrepancies in the estimation of dynamic and static reserves. To address these issues

a comprehensive set of criteria for identifying different types of carbonate reservoirs in the oilfield was developed. This was based on conventional well log data

thin section analyses

limited core data

and information from well tests and production characteristics. The reservoirs were categorized into three main types: fracture

fracture-vuggy

and porous. A detailed three-dimensional numerical well-testing model was created to accurately predict high-quality reservoir zones. This model took into account the reservoir's horizontal and vertical heterogeneity

allowing for precise delineation and assessment of the reservoir boundaries and connectivity in complex wells. It also facilitated a more accurate evaluation of the dynamic reserves and confirmed the oil and gas potential in the submerged mountains at the boundary of the Archaean group. This comprehensive approach laid the groundwork for devising strategic adjustments during the latter stages of the oilfield's development. It guided field modifications aimed at maximizing the reservoir's potential

ultimately leading to validated high production outcomes.